scaccag at stanford.edu
Mon Sep 6 18:32:05 PDT 2004
thanks for your answer, I developed and inspected at the optical
microscope my chip: everything seemed fine: I could see very small
stitching error in underexposed lines, but I think that it was within
specs (really hard to see). I wrote a few patterns (800 um-long
waveguides) over ~1x1.5 cm^2 and no visible errors in any of them. Some of
the lines far away from my focus points were slightly rough but I assume
that's because I was starting to go out of focus (sample tilted).
So, in conclusion, at least at the optical microscope, everything seems
I received also a notice from another user, Charis:
> hi guys,
> i noticed in my write today that the raith is takin unusually long.
> it even stops in empty write fields and shows 'stitching wait' for 3s.
> what is this 'stitching wait' and how do i turn it off? thanks.
Can you say anything about that? It happened to me in past that some
patterns which should write fast were actually written very slow and
sometimes with errors: it looked actually like there was an error in the
interpretation of the gds pattern, although it was displayed correctly in
the editor. It's a bit complicate to explain by email, but I can call you
or send you some detailed explanations if you want. Anyway, the time
required to write those patterns seemed to be pattern- and size-depent.
That's it for now, I will be able to give you more info about the sample
in a week or so (after finishing processing it and SEM it), if you need.
PS: I haven't checked the beam current at all aperture yet, I'll try to do
that this week
On Fri, 3 Sep 2004, Cole Loomis wrote:
> Hi Luigi,
> Thank you for the system update. I would like to hear how your exposure
> turns out, so please keep me posted. In reference to your
> questions/comments below, my comments are in BLUE.
> Thanks again,
> Cole Loomis
> Service Engineer
> Raith USA, Inc.
> 2805 Veteran's Hwy - Suite 23
> Ronkonkoma, NY 11779
> Office: (631) 738-9500 EXT: 16
> Fax: (631) 738-2055
> -----Original Message-----
> From: Luigi Scaccabarozzi [mailto:scaccag at stanford.edu]
> Sent: Thursday, September 02, 2004 10:01 PM
> To: cl at raithusa.com
> Cc: jwc at snf.Stanford.EDU
> Subject: raith status
> Hi ... (sorry, I'm not sure how to spell your name),
> I got your voice mail. I've been away the past two days, however this is
> what I can tell you: I just started an overnight write, everything seemed ok
> (beam quality, spot size, align writefield...) except one detail: the V zoom
> factor for 100um WF, 600X, 5mm WD, 10um aperture, 10keV was 1.52 whereas
> the U zoom factor was 1.49. I remember in past the two numbers were about
> the same (~1.49). A few weeks ago we had the problem of V zoom factor
> exceeding the range (which, BTW, is close to 1.52), and we could not write
> at 600x, but only at, say 570X. After a while the problem misteriously
> disappeared and zoom V factor got back to normal values (~1.49). This time
> the V factor didn't exceed the limit, so I started the write anyway.
> This zoom value depends on the calibration of the Electro-Optics board;
> which was replaced last week and recalibrated over several iterations. It
> is normal for these values to be slightly different, so if your
> align-writefield is working at a mag of 570, then leave it there. Please
> verify that the magnification display is correct: On the LEO PC, go to
> "Tools > User Preferences > SEM Conditions > Magnification Display" Make
> sure this is set to "Polaroid 545".
> Another comment is about the current: at 10 keV, 10um , after cleaning and
> bake I would expect a current of at least 0.025nA, whereas I measured only
> 0.0175 nA... has the column already got that bad?
> What are the beam current values for all apertures at 10keV? If they are
> all a little low, we could adjust the extractor voltage to increase the beam
> current. I highly doubt that the column is already contaminated. Since
> there were a few extractor trips on the system last week, the gun parameters
> might need some minor tweaking.
> Otherwise I didn't hear of any complain from other users.
> I will develop tomorrow morning and I'll be able to tell you more.
> I haev also one question about the piezos: I'm using small pieces (~ 1x 2
> cm) and trying to write on most of that area. I use the standard clips and I
> notice that it's hard to keep the focus over such area. Can I use the piezos
> for this purpose, or the piece is too small? what's the standard position of
> the piezos, for which the stage itself is flat? Should I "center the piezos"
> at the beginning of the session or leave them as they are after the warm up?
> The leveling piezo's are intended to level larger samples/wafers (2.5" and
> greater). As far as starting with a level sample holder...the Universal
> Sample Holder itself was not machined to the level of accuracy needed for
> leveling with these piezo's. In general, the system admin must go through
> the calibration procedure for each sample holder. In the window "Height
> Control", you can select the sample holder you are using, then select
> "LEVEL". This should adjust the piezo's to the pre-calibrated values.
> Before the recent service issues with the column, James was planning on
> calibrating the electro-static chuck. Once this is done, you will be able
> to level entire wafers. Another idea...if you are using the clips to secure
> your sample, try using larger samples. The further in the clip is on your
> sample, the less the sample will tilt.
> When James returns, ask him if he has calibrated the piezo's in the Height
> Control window. In the meantime, I would center the piezo's after loading a
> I'll write/call you tomorrow after developing tonight's sample. Regards
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